The function is chdir, not cd.  The 'cd' man page says that 'cd -P' should "perform actions equivalent to the chdir() function".

So, you are asking for a different function, which should *not* be named 'os.chdir'.  You'll have to make a case for it being useful enough to add.

The same applies to getcwd, which is also a wrapper for the posix function, not an emulation of the shell's pwd.